Molten-salt mediated thermochemical reactions using geothermal energy

Abstract

A method for producing hydrogen by thermochemical splitting of water includes injecting one or more feed streams of water into a reaction chamber. The method further includes using a molten salt heated by a subterranean heat source to carry out the thermochemical splitting of water to form hydrogen and oxygen in the reaction chamber. The formed products are subsequently removed from the reaction chamber. Hydrogen formed in the reaction chamber may be used in a downstream process to generate hydrocarbons.

What is claimed is: 
     
       1. A method for producing hydrogen by thermochemical splitting of water, the method comprising:
 injecting one or more feed streams comprising water into a reaction chamber; 
 receiving a molten salt heated in a wellbore extending into a subterranean heat source comprising a magma reservoir; 
 using the heated molten salt to heat the water in the reaction chamber, thereby forming hydrogen and oxygen in the reaction chamber by one or more thermochemical reactions; and 
 removing, from the reaction chamber, a first product stream comprising the formed hydrogen and a second product stream comprising the formed oxygen. 
 
     
     
       2. The method of  claim 1 , wherein the reaction chamber comprises a circulating fluidized bed of one or more non-volatile metal oxide catalysts. 
     
     
       3. The method of  claim 1 , wherein the reaction chamber comprises a volatile metal oxide catalyst. 
     
     
       4. The method of  claim 1 , wherein the one or more feed streams further comprise an iodine feed stream and a sulfur dioxide feed stream, or copper feed stream and a hydrochloric acid feed stream. 
     
     
       5. The method of  claim 1 , further comprising heating the molten salt in a heat exchanger disposed at a depth within the wellbore. 
     
     
       6. The method of  claim 1 , further comprising:
 transferring at least one of the first product stream or the second product stream to a separator vessel; 
 generating, using an absorption chiller, a cooling fluid using heat from the heated molten salt; 
 providing the cooling fluid to the separator vessel to cool the separator vessel; and 
 separating the at least one of the first product stream or the second product stream into one or more end products using the cooled separator vessel. 
 
     
     
       7. The method of  claim 1 , further comprising:
 providing the hydrogen to a downstream reaction system; 
 providing carbon dioxide to the downstream reaction system; and 
 using the downstream reaction system to convert the hydrogen and carbon dioxide into one or more hydrocarbon products. 
 
     
     
       8. The method of  claim 7 , wherein the one or more hydrocarbon products comprise a liquid phase hydrocarbon and a gas phase hydrocarbon, wherein the method further comprises:
 providing the one or more hydrocarbon products to recovery equipment; 
 generating, using an absorption chiller, a cooling fluid using heat from the heated molten salt; 
 using the cooling fluid to cool the recovery equipment; and 
 separating the liquid phase hydrocarbon from the gas phase hydrocarbon using the cooled recovery equipment.